For the midrange, which is better: the best 5" in a box (sealed/aperiodic/vented) or the best 6.5" open-baffled?

I've heard that >6" drivers do not have the clarity in the midrange that the best 5" drivers do. However, they have lower distortion in the lower frequencies and are more suitable for open-baffle designs, which AFAIK improves midrange clarity.